Pipe Marker Sizing & Ordering Guide: Getting AS 1345 Colours and Dimensions Right

A pipe marker is one of the cheapest items on the store, and one of the easiest to get wrong at the checkout. Order a label sized for a large steel main and wrap it around a small copper line, and it curls at the edges and the arrow all but disappears. Order the wrong colour, and the label actively misleads whoever reads it next. This guide is about getting the AS 1345 colour and the size right before you order, not after the box arrives.

What a pipe marker actually is

A pipe marker is a self-adhesive vinyl label that wraps around the outside of a pipe, rather than a sign fixed to a wall or a post nearby. It carries the pipe's contents in bold text, a background colour tied to what is inside the pipe, and an arrow at each end showing which way the pipe flows.

Every marker in the range ships with an arrow chevron pointing in both directions. The installer trims off whichever end does not match the actual flow and applies the label with the remaining arrow pointing the right way. It is a small detail, but it means one product covers a pipe running left to right or right to left without a separate line item for each.

AS 1345, and what the colour is actually telling you

AS 1345 is the Australian Standard covering identification of the contents of pipes, conduits and ducts, and it is the standard behind every colour on this page. Rather than leave colour to whoever is ordering the sign, AS 1345 assigns a base colour to each broad category of contents, so colour alone tells a worker, a contractor or an emergency responder roughly what is inside before they read a word of text.

• Green, water
• Brown, oils and flammable liquids
• Yellow-ochre, gases
• Violet, acids and alkalis
• Light blue, air
• Black, miscellaneous
• Red, fire services
• Orange, electrical
• White, communications
• Dark blue, supplementary services

For the full detail on how each colour is meant to be read on site, and how AS 1345 expects markers to be spaced along a run, see our complete guide to AS 1345 pipe identification .

The three sizes, and matching the label to the pipe

Getting the colour right and the size wrong is the most common ordering mistake on this range. The pipe marker labels range ships in three sizes, each tied to a pipe diameter rather than to the pipe's function:

• Large, 475 x 60mm, for pipes over 75mm in diameter
• Medium, 475 x 35mm, for pipes between 40mm and 75mm
• Small, 100 x 200mm, sold as a sheet of 14, for pipes under 40mm

A label sized for a large steel main wrapped around a narrow copper line will not sit flat, and the arrow ends up compressed into the pipe's own curve. A label sized for a small pipe stretched over a large main reads thin from a normal working distance and does the opposite of what a marker is for. Measure the pipe's actual outside diameter before ordering, and pick the size against that figure rather than the nominal pipe size printed on a drawing.

Every pipe marker in the range follows the same three-size ladder, in self-adhesive vinyl, whatever the wording on it. That is the whole services list, not a handful of common ones: compressed air, gas and water, but equally acetylene, chilled water flow and return, CIP supply and return, caustic, chlorine, condensate and the rest. Apply the label to a clean, dry section of pipe so the adhesive holds. Where the exact wording is not in stock, a customised marker is made to the same three sizes.

Where a pipe marker sits alongside other signage

A pipe marker tells someone standing next to the pipe what is inside it. It does not replace the hazard information a violet acid line or a brown flammable liquid line often needs at a bulk storage point, a decanting station or a connection to plant, which is a separate layer covered in our guide to chemical and hazardous substance signs . A dangerous goods diamond fixed near a valve or a tank connection is doing a different job again, warning from a distance rather than identifying a specific run, and the dangerous goods diamonds range covers that side of it.

Pipe runs on a mining or remote processing site can extend for hundreds of metres between the plant room and the boundary fence, and a correctly sized, correctly coloured marker matters even more where it might be the only clue a visiting contractor or a new starter has. Our guide to mining and remote site safety signs covers what else that kind of site typically needs.

An ordering checklist before you check out

• Measure the pipe's actual outside diameter, not the nominal size on a drawing or a spec sheet.
• Match that figure against the ladder: Large over 75mm, Medium 40mm to 75mm, Small under 40mm.
• Confirm the AS 1345 colour matches what is flowing through the pipe today, which is not always what it was built to carry.
• Order enough for every junction, valve and wall penetration on the run, not only the two ends.
• If the exact wording is not stocked, a customised marker is made to the same three sizes.

Browse the pipe marker labels range to match the ladder above against what is actually on your pipe.